washington as new evidence of chemical weapons are now in play in the country. president obama has said crossing that line would be a game changer. now critics are calling the credibility into question while the white house says it wants more evidence. nbc's tracie potts is live for us in washington. tracie, good morning. >> reporter: good morning. that's why some lawmakers here on capitol hill say the u.s. needs to send a strong signal not only to the assad regime in syria but also to others who may be watching, and all that's underscored by the new violence there this morning. the country's prime minister survived an assassination attempt today. his convoy was bombed. there are varying reports of other deaths and injuries. now the u.s. has some evidence syria's government may have used chemical weapons on its own people. president obama had called that a red line for action. now he's cautious. >> knowing that potentially chemical weapons have been used inside of syria doesn't tell us when they were used, how they were used. >> reporter: there's pressure from capitol hill to act soon.

attempt on monday. >>> meanwhile, president obama is expressing concern that russian leader vladimir putin, after the reported use of chemical weapons in syria, the white house says use of such weapons would be a game changer, but the pentagon says it will not speculate on any intervention plans. >>> the faa is investigating a deadly mid-air collision of two small planes. the faa says a single-engine cessna landed on a golf course in southern california on monday after colliding with another cessna about eight miles north of ventura. all three on board that plane sustained only minor injuries. in the mountains northwest of santa monica, firefighters combed through smoking wreckage of the second plane and recovered the pilot's body. it's believed he was the only one on board there. >>> parts of eastern iowa dealing with severe weather, a heavy round of hail ranging from pea size to as large as two inches falling in waterloo, causing millions of dollars in damage to cars. the hail left covering that, and some places looking more like snow. bill karins, nbc meteorologist here w